Sensors are used to monitor a wide variety of compounds in various environments, including in vivo analytes. The quantitative determination of analytes in humans and mammals is of great importance in the diagnoses and maintenance of a number of pathological conditions. Illustrative analytes that are commonly monitored in a large number of individuals include glucose, lactate, cholesterol, and bilirubin. The determination of glucose concentrations in body fluids is of particular importance to diabetic individuals, individuals who must frequently check glucose levels in their body fluids to regulate the glucose intake in their diets. The results of such tests can be crucial in determining what, if any, insulin and/or other medication need to be administered.
Analyte sensors typically include components that convert interactions with analytes into detectable signals that can be correlated with the concentrations of the analyte. For example, some glucose sensors use amperometric means to monitor glucose in vivo. Such amperometric glucose sensors typically incorporate electrodes coated with glucose oxidase, an enzyme that catalyzes the reaction between glucose and oxygen to yield gluconic acid and hydrogen peroxide (H2O2). The H2O2 formed in this reaction alters an electrode current to form a detectable and measurable signal. Based on the signal, the concentration of glucose in the individual can then be measured.
An important component of analyte sensors and systems are the electrodes used to measure these signals. Based on various factors such as its design, plating, and the materials used, an electrode may vary in terms of its stability, reliability, and sensitivity in detecting analyte signals. In particular, electrode design plays an important role in the manufacturing of electrodes since it can determine how electric charges flow or build-up on electrodes. Generally, during the electroplating process, the intrinsic nature of electric charges is to accumulate at the edges of the electrode, especially at sharp edges and corners. This can create issues of edge growth and uneven plating thickness when the electrode is electroplated with an electrically conductive material. Furthermore, the non-uniform plating thickness often makes it harder to smoothly and uniformly dispose subsequent coatings and layers onto the electrode.
There is a need in the art for sensor electrode designs that can avoid undesirable issues associated edge growth. There is also a need for sensor electrodes and analyte sensor systems that have high stability, reliability, and sensitivity in detecting analyte signals. Embodiments of the invention disclosed herein meet these as well as other needs.